An eruv (Hebrew: עירוב‎ mixture, also transliterated as eiruv or erub, plural: eruvin) is a ritual enclosure that traditionally observant Jewish communities construct in their neighborhoods as a way to permit the transference of objects from one domain type to another. For example carrying an object from indoors (a private domain) to a public street (a public domain) on Shabbat, which they would otherwise understand to be prohibited by Jewish law (Halakha).

The eruv permits traditionally observant Jews to, among other things, carry keys, tissues, medicines, or babies with them, and to use strollers and canes. The presence or absence of an eruv thus especially affects the lives of people with limited mobility and those responsible for taking care of babies and young children.

Transferring between domains Hebrew: מוציא מרשות לרשות / הוצאה

Definition: Transferring something from one domain type to another domain type.

Chapters 1 and 11 of Talmud tractate Shabbat deals with the melakha of transferring from one domain to another, commonly called "carrying".